diff --git a/README.md b/README.md
index 205617c..c95e4fa 100644
--- a/README.md
+++ b/README.md
@@ -203,6 +203,24 @@ invisible_playwright version        # wrapper and binary versions
 invisible_playwright clear-cache    # remove all cached binaries
 ```
 
+## Known issues
+
+### `headless=True` on Windows can cause tab crashes on sites with heavy cross-process navigation
+
+Reported as [#18](https://github.com/feder-cr/invisible_playwright/issues/18) (`id.sky.com` and similar). On Windows, `headless=True` runs Firefox headed on a hidden alt-desktop created via `CreateDesktop`. Some sites (id.sky.com, anything else loading Adobe AppMeasurement in a way that triggers cross-process navigation) end up firing `page.on('crash')` after about 10 seconds. The cause is a window-parenting interaction between the alt-desktop and the GPU/content processes; the workaround is one of:
+
+```python
+# Option A — keep the visible window (no alt-desktop)
+with InvisiblePlaywright(seed=42, headless=False) as browser:
+    ...
+
+# Option B — run inside Xvfb on Linux (alt-desktop bug is Windows-only)
+```
+
+The visible window case works on every site we've tested. Linux + Xvfb is unaffected.
+
+---
+
 ## Related projects
 
 invisible_playwright takes a different angle than the major Firefox-hardening projects but stands on their shoulders:
diff --git a/src/invisible_playwright/prefs.py b/src/invisible_playwright/prefs.py
index 43ece27..496fd04 100644
--- a/src/invisible_playwright/prefs.py
+++ b/src/invisible_playwright/prefs.py
@@ -384,6 +384,21 @@ _WIN_VIRT_DESKTOP_WORKAROUNDS: Dict[str, Any] = {
     # Bugzilla refs: 1798091, 1524591, 1229829. Lowering the GPU sandbox to 0
     # restores hardware compositor + functional WebGL on alt desktops.
     "security.sandbox.gpu.level": 0,
+    # Same root cause as above, content process side. Wrapper repo issue #18
+    # (id.sky.com tab crash). Sandbox content level > 4 puts content processes
+    # on the sandbox's own kAlternateWinstation (see
+    # security/sandbox/win/src/sandboxbroker/sandboxBroker.cpp line 1113-1114:
+    # `if (aSandboxLevel > 4) config->SetDesktop(kAlternateWinstation)`).
+    # Combined with our CreateDesktop alt-desktop, that puts browser process
+    # and content processes on DIFFERENT desktops. Cross-process navigation
+    # (Adobe AppMeasurement → new origin → new content process on a new
+    # desktop) then fails window parenting between parent and child → content
+    # process exits cleanly (exitCode=0, signal=null) and Playwright fires
+    # page.on('crash') ~10s after page load. Lowering content sandbox to 4
+    # keeps content processes on the same desktop as the browser process,
+    # which is what we want here (and is still tight enough — level 4
+    # blocks file/registry write, network calls, hardware access).
+    "security.sandbox.content.level": 4,
 }